Msg 8114, Level 16, State 5, Line 2 Error converting data type

Can you help me to do this view correctly?

code:

SELECT CustomerName, C_CUR, SUM(BILL_AMT) AS B_AMT, C_CODE
FROM     dbo.BILLS
WHERE  (BILL_TYPE = 2)
GROUP BY C_CODE, C_CUR, CustomerName
      UNION ALL
SELECT C_CODE, SUM(BILL_AMT) AS RT_AMT, C_CUR, CustomerName
FROM     dbo.RTN_BILLS
WHERE  (BILL_TYPE = 2)
GROUP BY C_CODE, C_CUR, CustomerName

error:

Msg 8114, Level 16, State 5, Line 2
Error converting data type nvarchar to float.

>Solution :

List the columns for both parts of the UNION in the same order.